Once you check the box, you won’t be asked again about a verification code as long as you’re using the same device and same browser and have cookies enabled.
Verification codes are designed to verify your identity, so by checking the box you’re telling TaxAct that no one else is using your computer or device has access to your information.
If you want to keep receiving verification codes but need to update your email address, or if you want to receive the codes via text, add or edit the information in your account.